2.3Milestones in the Understanding of the Ocean

Figure 2.7 The 1786 version of Franklin-Folger map of the Gulf Stream.

beginning with the first scientific investigations of the 17th century. Initially progress was slow. First came very simple observations of far reaching importance by scientists who probably did not consider themselves oceanographers, if the term even existed. Later came more detailed descriptions and oceanographic experiments by scientists who specialized in the study of the ocean.

1685 Edmond Halley, investigating the oceanic wind systems and currents, published “An Historical Account of the Trade Winds, and Monsoons, observable in the Seas between and near the Tropicks, with an attempt to assign the Physical cause of the said Winds” Philosophical Transactions.

1735 George Hadley published his theory for the trade winds based on conservation of angular momentum in “Concerning the Cause of the General Trade-Winds” Philosophical Transactions, 39: 58-62.

1751 Henri Ellis made the first deep soundings of temperature in the tropics, finding cold water below a warm surface layer, indicating the water came from the polar regions.

1769 Benjamin Franklin, as postmaster, made the first map of the Gulf Stream using information from mail ships sailing between New England and England collected by his cousin Timothy Folger (figure 2.7).

1775 Laplace’s published his theory of tides.

1800 Count Rumford proposed a meridional circulation of the ocean with water sinking near the poles and rising near the Equator.

1847 Matthew Fontaine Maury published his first chart of winds and currents based on ships logs. Maury established the practice of international exchange of environmental data, trading logbooks for maps and charts derived from the data.

1872–1876 Challenger Expedition marks the beginning of the systematic study of the biology, chemistry, and physics of the ocean of the world.

1885 Pillsbury made direct measurements of the Florida Current using current meters deployed from a ship moored in the stream.

1903 Founding of the Marine Biological Laboratory of the University of California. It later became the Scripps Institution of Oceanography.

1910–1913 Vilhelm Bjerknes published Dynamic Meteorology and Hydrography which laid the foundation of geophysical fluid dynamics. In it he developed the idea of fronts, the dynamic meter, geostrophic flow, air-sea interaction, and cyclones.

1930 Founding of the Woods Hole Oceanographic Institution.

1942 Publication of The ocean by Sverdrup, Johnson, and Fleming, a comprehensive survey of oceanographic knowledge up to that time.

Post WW 2 The need to detect submarines led the navies of the world to greatly expand their studies of the sea. This led to the founding of oceanography departments at state universities, including Oregon State, Texas A&M University, University of Miami, and University of Rhode Island, and the founding of national ocean laboratories such as the various Institutes of Oceanographic Science.

1947–1950 Sverdrup, Stommel, and Munk publish their theories of the winddriven circulation of the ocean. Together the three papers lay the foundation for our understanding of the ocean’s circulation.

1949 Start of California Cooperative Fisheries Investigation of the California Current. The most complete study ever undertaken of a coastal current.

1952 Cromwell and Montgomery rediscover the Equatorial Undercurrent in the Pacific.

1955 Bruce Hamon and Neil Brown develop the CTD for measuring conductivity and temperature as a function of depth in the ocean.

1958 Stommel publishes his theory for the deep circulation of the ocean.

1963 Sippican Corporation (Tim Francis, William Van Allen Clark, Graham Campbell, and Sam Francis) invents the Expendable BathyThermograph xbt now perhaps the most widely used oceanographic instrument deployed from ships.

1969 Kirk Bryan and Michael Cox develop the first numerical model of the oceanic circulation.

1978 nasa launches the first oceanographic satellite, Seasat. The project developed techniques used by generations of remotes sensing satellites.

1979–1981 Terry Joyce, Rob Pinkel, Lloyd Regier, F. Rowe and J. W. Young develop techniques leading to the acoustic-doppler current profiler for measuring ocean-surface currents from moving ships, an instrument widely used in oceanography.

1988 nasa Earth System Science Committee headed by Francis Bretherton outlines how all earth systems are interconnected, thus breaking down the barriers separating traditional sciences of astrophysics, ecology, geology, meteorology, and oceanography.

1991 Wally Broecker proposes that changes in the deep circulation of the ocean modulate the ice ages, and that the deep circulation in the Atlantic could collapse, plunging the northern hemisphere into a new ice age.

1992 Russ Davis and Doug Webb invent the autonomous, pop-up drifter that continuously measures currents at depths to 2 km.

1992 nasa and cnes develop and launch Topex/Poseidon, a satellite that maps ocean surface currents, waves, and tides every ten days, revolutionizing our understanding of ocean dynamics and tides.

1993 Topex/Poseidon science-team members publish first accurate global maps of the tides.

More information on the history of physical oceanography can be found in Appendix A of W.S. von Arx (1962): An Introduction to Physical Oceanography.

Data collected from the centuries of oceanic expeditions have been used to describe the ocean. Most of the work went toward describing the steady state of the ocean, its currents from top to bottom, and its interaction with the atmosphere. The basic description was mostly complete by the early 1970s. Figure 2.8 shows an example from that time, the surface circulation of the ocean. More recent work has sought to document the variability of oceanic processes, to provide a description of the ocean su cient to predict annual and interannual variability, and to understand the role of the ocean in global processes.

2.4Evolution of some Theoretical Ideas

A theoretical understanding of oceanic processes is based on classical physics coupled with an evolving understanding of chaotic systems in mathematics and the application to the theory of turbulence. The dates given below are approximate.

19th Century Development of analytic hydrodynamics. Lamb’s Hydrodynamics is the pinnacle of this work. Bjerknes develops geostrophic method widely used in meteorology and oceanography.

1925–40 Development of theories for turbulence based on aerodynamics and mixing-length ideas. Work of Prandtl and von Karman.